var doors : array [1..100] of Boolean;
var i, j : Integer;

for i:=1 to 100 do
   for j:=i to 100 do
      if (j mod i)=0 then
         doors[j] := not doors[j];

for i:=1 to 100 do
   if doors[i] then
      PrintLn('Door '+IntToStr(i)+' is open');